SAT II Physics Test Format

Directions: Each set of lettered choices below refers to the numbered questions immediately following it. Select the one lettered choice that best answers each question and then blacken the corresponding space on the answer sheet. A choice may be used once, more than once, or not at all in each set.

Questions 1–3

A:

A boy throws a ball straight up in the air and then catches it again.

1. Which of the above graphs best represents the ball’s position with respect to time?
2. Which of the above graphs best represents the ball’s velocity with respect to time?
3. Which of the above graphs best represents the ball’s acceleration with respect to time?

Explanation

You can usually answer classification questions a bit more quickly than the standard five-choice completion questions, since you only need to review one set of answer choices to answer a series of questions.

The answer to question 1 is B. The ball’s position with respect to time can be expressed by the equation y = –1/2 gt², where g is the downward, acceleration due to gravity. As we can see, the graph of y against t is an upside-down parabola. In more intuitive terms, we know that, over time, a ball thrown in the air will rise, slow down, stop, and then descend.

The answer to question 2 is E. The acceleration due to gravity means that the velocity of the ball will decrease at a steady rate. On the downward half of the ball’s trajectory, the velocity will be negative, so E, and not A, is the correct graph.

The answer to question 3 is D. The acceleration due to gravity is constant throughout the ball’s trajectory, and since it is in a downward direction, its value is negative.

Don’t worry if the question confused you and the explanations didn’t help. This material and more will be covered in Chapter 2: Kinematics. This was just an exercise to show you how a classification question is formatted.

These are the multiple-choice questions we all know and love, and the lifeblood of any multiple-choice exam. You know the drill: they ask a question, give you five possible answer choices, and you pick the best one. Got it? Good. An example appears below.

While you’ll often find two or three questions in a row that deal with the same topic in physics, there is no pattern. You might find a question on modern physics followed by a question on dynamics followed by a question on optics. However, there is a general tendency for the questions to become more difficult as you progress.

Directions: Each of the questions of incomplete statements below is followed by five suggested answers or completions. Select the one that is best in each case and then fill in the corresponding oval on the answer sheet.

A gas in a closed container is steadily heated over a period of time. Which of the following statements is true of this process?

1. The average kinetic energy of the gas molecules decreases
2. The mass of the container increases
3. The pressure exerted by the gas on the walls of the container increases
4. The gas changes phase into a liquid
5. The specific heat of the gas decreases

Explanation

The answer to this question is C. The key lies in remembering the ideal gas law: PV = nRT. According to this formula, an increase in temperature is accompanied by an increase in pressure. A is wrong, since the average kinetic energy of gas molecules corresponds to their temperature: if the temperature increases, so does the average kinetic energy of the molecules. B is wrong because we’re dealing with a closed container: the mass cannot either increase or decrease. D is wrong because a gas must be cooled, not heated, to change phase into a liquid. Finally, E is wrong because the specific heat of any substance is a constant, and not subject to change. We’ll touch on all this and more in Chapter 9: Thermal Physics.